uBlox compass configuration problems - east is west - Discussions

Hi all,
I can't find a good description of how to calibrate your compass and I also have some problems with my compass' readings.

I have a Pixhawk autopilot module and a 3DR uBlox GPS/compass module. Connecting this module is simple (my compass is connected through the I2C splitter so not directly to the Pixhawk). In mission planner I want to set-up my compass so I did the following:

1. Connect via COM to Pixhawk

2. Go to: 'Initial setup' -> 'Mandatory Hardware' -> 'Compass'.

3. Choose the option: 'APM with External Compass' AND select 'rotation_none' from the drop down menu next to 'Manual'. I selected 'rotation_none' because my GPS/compass module is upside down and the arrow is pointing in the same direction as the arrow on the Pixhawk, so a belly-to-belly set-up.

4. Click 'Live Calibration' and turn a bit with the Pixhawk.

But.... when I now check my compass readings in 'Flight Data' I get this very weird result: North is not were North is AND East and West are switched. So if I turn 90degrees clockwise starting from North my compass says he is looking to the West...

Note: how do you know if the new settings "external compass" have been saved? Because when I open the compass tab a second time the checkbox is at 'Manual' again and not 'External'

Also, I've read that if you connect the uBlox module to Pixhawk, the internal compass is automatically turned off, although I have a fealing that both are turned on, because if you turn (yawing) either of the two modules seperately the measured heading in mission planner changes.

Can anyone help me?

Note to webdesigners: Is it possible to make a new category with 'Compass'?

Replies

Admin

Thomas J Coyle III February 18, 2014 at 5:44am

@Menno,

If you are using the GPS/Compass module with a Pixhawk, why are you selecting "AMP with External Compass"?

You should be selecting the Pixhawk/PX4 option at the top of the selection list.

Regards,

TCIII ArduRover2 Developer
- Menno Hochstenbach > Thomas J Coyle III February 18, 2014 at 6:18am
  
  Because that option shows a picture of the uBlox GPS/compass module that I'm using. And because my compass is external.... Should I select Pixhawk/PX4 then? But how does mission planner then know that I also have an external compass connected to the I2C port on the Pixhawk?
  - Admin
    
    Thomas J Coyle III > Menno Hochstenbach February 18, 2014 at 9:08am
    
    @Menno,
    
    You have a Pixhawk. Read these Wiki instructions for the Pixhawk: GPS/Compass
    
    Select the Pixhawk/PX4 option for the compass setup.
    
    Regards,
    
    TCIII ArduRover2 Developer
    - Bret C > Thomas J Coyle III September 20, 2014 at 5:43pm
      
      Also - after calibration should I be able to check the aircraft with a compass to verify that the direction it is setting is the actual direction it is pointing on the mission planner?
    - Bret C > Thomas J Coyle III September 20, 2014 at 5:39pm
      
      Guys I need clarification here. So I am setting up a plane with a Pixhawk a and external compass. So I select the "pixhawk/Px4?" Seams strange there is a photo of an external 3DR compass but that is not what we should select?
    - Menno Hochstenbach > Thomas J Coyle III February 18, 2014 at 9:20am
      
      I followed the instructions.. but the compass gives bad readings. I'll put a picture below of how the compass is mounted (the arrows of both the pixhawk and ublox are pointing to the left). Since the ublox is upside down here (and the compass is upside down in the ublox) I should select "rotation none" right?
      PS, I clicked "yes" when mission planner asked "FW version greater than APM:copter 3.01"?
      The picture below shows my selections before I click "Live Calibration" to configure the compass:
      - Admin
        
        Thomas J Coyle III > Menno Hochstenbach February 18, 2014 at 9:28am
        
        @Menno,
        
        Is it necessary to have the GPS/Compass attached to the bottom of the Pixhawk?
        
        I do not recommend that configuration.
        
        Mount the GPS/Compass so that it is right side up and facing the same direction as the Pixhawk arrow.
        
        Regards,
        
        TCIII ArduRover2 Developer
        
        Menno Hochstenbach > Thomas J Coyle III February 18, 2014 at 10:15am
        
        It's not necessary and I don't know yet how it will be in the final set up, but this is easy if you want keep both modules parallel during the configuration.... But no matter how they are mounted in the end, the compass should work, but it doesn't
        
        Moderator
        
        Gary Mortimer > Menno Hochstenbach February 18, 2014 at 11:15am
        
        That's the GPS orientation for those of us in the Southern Hemisphere Thomas.
        
        Menno Hochstenbach > Gary Mortimer February 19, 2014 at 12:17am
        
        Is this a joke, or is there hemispheric dependence? Note that I'm talking about the compass (not GPS).

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